STILL will not start!!

[Punk'd]

I just replaced the intake valves after the cam chain snapping and bending them. Thought it would fire right up, well guess what happened.. IT DIDNT!

I have no idea what the problem can be now, Unless there is some lineing up to do with the flywheel after putting a new cam chain on or whatever..

Someone please help:confused:

[lumi]

take it little by litte first lets start from the top of the engine,

getting spark?

any leaks and fluids to level?

valves clearances, decomp setting?

hows the timing line up from the small hole on corner with timing sprocket?


if im correct the flywheel should have a correct timng mark aswell on it?


see how this all plays and we can continue




-lumi

[ghott]

Gas turned on? :)

[Punk'd]

Originally posted by lumi
take it little by litte first lets start from the top of the engine,

getting spark?

any leaks and fluids to level?

valves clearances, decomp setting?

hows the timing line up from the small hole on corner with timing sprocket?


if im correct the flywheel should have a correct timng mark aswell on it?


see how this all plays and we can continue




-lumi

I grounded the spark plug, And it sparks. So we can check that off.

No leaks, all fluids are to level.

Valves clearances (same as stock), decomp setting (I no nothing about that)

The timing will only line up if I force the bike foward and hold it. Otherwise the cam tends to rotate to the left or to the right.

I know nothing about a timing mark on the flywheel??

[Punk'd]

Originally posted by ghott
Gas turned on? :)

Yes, gas is on. I even had a little come out of the carb into the airbox. I dont know why either:grr:

[ghott]

All hoses and line reconnected correctly?

I don't believe I've ever had gas into my airbox....is your carb seated correctly?

[Punk'd]

Originally posted by ghott
All hoses and line reconnected correctly?

I don't believe I've ever had gas into my airbox....is your carb seated correctly?

Yes, everythings connected correctly, Im not sure how it happened either:huh

[DJJ450r]

when i stand mine up some goes throug the filter and into the airbox, not much tho

[GPracer2500]

Originally posted by Punk'd
Yes, gas is on. I even had a little come out of the carb into the airbox. I dont know why either:grr:

Spark, fuel, compression--it all comes down to those three things.

If your getting spark and you've got fuel then I'm gussing you're not getting compression because your cam timing is off. That might explain why you're getting fuel in your airbox too.

Check the cam timing using the procedure outlined in the service manual.

[Punk'd]

Originally posted by GPracer2500
Spark, fuel, compression--it all comes down to those three things.

If your getting spark and you've got fuel then I'm gussing you're not getting compression because your cam timing is off. That might explain why you're getting fuel in your airbox too.

Check the cam timing using the procedure outlined in the service manual.

The plug that is in there is the original plug. I grounded it and it sparked. Does this matter? Could this still be a reason it wont start even though it sparks?

My cam timing is dead on though? but like I said.. In order for it to be dead on, I have to hold it or the cam sprocket rotates left or right. Can the flywheel contribute to any of these problems?

[HAVOK]

Originally posted by Punk'd


Valves clearances (same as stock), decomp setting (I no nothing about that)




If you have the stage two in ,the stock valve setting is wrong.
And if the decomp is off it will make it hard to start.
Gas will leak from carb when you stand it up on the rear. You have to turn the gas off then drain the carb via drain screw.

[Punk'd]

Originally posted by HAVOK
If you have the stage two in ,the stock valve setting is wrong.
And if the decomp is off it will make it hard to start.
Gas will leak from carb when you stand it up on the rear. You have to turn the gas off then drain the carb via drain screw.

Decomp? How do you reset it if its off?

I havent stood it up on the grab bar for it to leak gas. Alittle just came out when I went on a kicking spree trying to get it to start:mad:

[HAVOK]

It is the thing that is over the right side ex valve. It is easy loosen the lock nut, put corect feeler in gap screw down and tightin lock nut, pull feeler out.
Do you have a service book? If not you can download one over at the .org.

[Punk'd]

Originally posted by HAVOK
It is the thing that is over the right side ex valve. It is easy loosen the lock nut, put corect feeler in gap screw down and tightin lock nut, pull feeler out.
Do you have a service book? If not you can download one over at the .org.

I have a internet version, but I cant find anything on how to do that? Could this very well be my problem?

And what about that spark plug.. It still sparks, but i've heard it doesnt matter. Some people have gotten spark, but there bikes didnt start untill they purchased a new plug. Any truth to this?

[GPracer2500]

Originally posted by Punk'd
....In order for it to be dead on, I have to hold it or the cam sprocket rotates left or right...

Not sure I get what's going on there. Makes me wonder if it's as dead-on as you believe it to be....I don't know--I'm just saying....

To confirm the cam timing you line up the punch mark on the primary drive gear (under the inspection cover down on the side of the crankcase) with the index mark on the right crankcase cover. That's how you find TDC. Then confirm that the timing mark on the cam sprocket lines up with the index mark on the cam tower.

The decomp clearance adjustment is covered in the maintenance section (section 4).

[Punk'd]

Originally posted by GPracer2500
Not sure I get what's going on there. Makes me wonder if it's as dead-on as you believe it to be....I don't know--I'm just saying....

To confirm the cam timing you line up the punch mark on the primary drive gear (under the inspection cover down on the side of the crankcase) with the index mark on the right crankcase cover. That's how you find TDC. Then confirm that the timing mark on the cam sprocket lines up with the index mark on the cam tower.

The decomp clearance adjustment is covered in the maintenance section (section 4).


Is it possible I do have the timing correct, but maybe its not on the TDC of the compression stroke? Isnt there two TDC's?

How do you tell them apart?

[QuadRacer041]

Originally posted by Punk'd
Is it possible I do have the timing correct, but maybe its not on the TDC of the compression stroke? Isnt there two TDC's?

How do you tell them apart?


yes there are 2 tdc's to tell them apart you want to be on the compression stroke. with the timing marks both lined up the cam lobes should be facing the rear of the quad, thats the compression stroke. if your cam lobes are gacing the front your on the exhaust stroke and thats 180 off. make sure your timing marks are lined up its crucial

[Punk'd]

Originally posted by QuadRacer041
yes there are 2 tdc's to tell them apart you want to be on the compression stroke. with the timing marks both lined up the cam lobes should be facing the rear of the quad, thats the compression stroke. if your cam lobes are gacing the front your on the exhaust stroke and thats 180 off. make sure your timing marks are lined up its crucial

Oh ok, Yeah I always make sure the lobes are facing my airbox.

Im going to try a spark plug, even though it does spark, but can someone tell me if the flywheel can contribute to any of these problems i've been having?

[QuadRacer041]

Originally posted by Punk'd
Oh ok, Yeah I always make sure the lobes are facing my airbox.

Im going to try a spark plug, even though it does spark, but can someone tell me if the flywheel can contribute to any of these problems i've been having?


well it can if its not timed right. but theres a key way so it will line up in the right position. if the key falls out and you didnt know it you you probably dont have the flywheel timed right.

[HAVOK]

What cam do you have in there?
If you have the stage two in there you will need too get hc2 valve spec and decomp specs.
Stock settings will not work with that cam.

[ghott]

HC2 Valve clearances are still supposed to be .011" for exhaust valves, and .006" for intake valves.

[BSTURDIVANT]

Change the cam and it will run!!! when you smack the valves hard enough to bend them, it rotates the hub on the cam enough to cause your decompressor to be open when fireing!! Already had this to happen! Bought a HRC cam off the internet that had been in the same broken chain incident. Wouldn't start and found the problem. We weld ours now!

[Punk'd]

Originally posted by BSTURDIVANT
Change the cam and it will run!!! when you smack the valves hard enough to bend them, it rotates the hub on the cam enough to cause your decompressor to be open when fireing!! Already had this to happen! Bought a HRC cam off the internet that had been in the same broken chain incident. Wouldn't start and found the problem. We weld ours now!

So your saying it could be the cam? How will it look if its messed up? Ill try putting the stock one back in if all else fails..

[lumi]

seems to me if timing is on, timing chain sprocket dead on, side hole on right side is lined up, and the flywheel is timed correctly you can rule out timing! Right have you check the cam lobes to be to the back and the lines on the small hold and sprocket to line up? and flywheel?



next would be decomp setting if you have a hc2???


you will have to increase the compression a bit more to make it fire, funny i havent heard this issue lately on the hc2 i thought they fixed it. you will have to set your decomp setting a bit tigher or looser not 100% sure , more than stock setting to make it fire up with the new cam, it is a drop in, with the valve clearance compared to stock but somtimes the cam will throw your decomp setting off.

after that i think a leaking carb into the box means jetting?



-lumi

[Punk'd]

Originally posted by lumi
seems to me if timing is on, timing chain sprocket dead on, side hole on right side is lined up, and the flywheel is timed correctly you can rule out timing! Right have you check the cam lobes to be to the back and the lines on the small hold and sprocket to line up? and flywheel?



next would be decomp setting if you have a hc2???


you will have to increase the compression a bit more to make it fire, funny i havent heard this issue lately on the hc2 i thought they fixed it. you will have to set your decomp setting a bit tigher or looser not 100% sure , more than stock setting to make it fire up with the new cam, it is a drop in, with the valve clearance compared to stock but somtimes the cam will throw your decomp setting off.

after that i think a leaking carb into the box means jetting?



-lumi


Im pretty sure timing is correct.. When my valves bent, i had to take everything apart to get to them.. Is it possible that I rotated it 180 degrees and put it back togther with the lobes facing back thinking its on the compression stroke but really not?

[duke416ex]

I think you are 180 off on the cam. When you have the cam at tdc the dot on the sprocket on the transmission side lines up with the arrow right? There is also a dot on that sprocket 180 out. All you have to do is loosen the cam sprocket bolts rotate the engine with that sprocket until it is aligned with the other dot and then tighten the bolts back down. If you are 180 out this will put you back right.

Being 180 out could also cause a little gas to be blown back through the carb and into the air box, so just a thought. And if the decompression is not right, it can cause the engine not to start.

[GPracer2500]

It's impossible to be exactly 180 degrees out of time. If you're at TDC on the compression stroke, everything is timed correctly, you remove the cam and reinstall 180 from where you started, all you've done is flip-floped the compression stroke with the exhaust stroke. You'd now be at TDC on the exhaust stroke. Spin the crank 360 degrees and your right back to TDC on the compression stroke with everything still in time even though you removed the cam and spun it 180 degrees.

Since the plug fires every stroke (i.e. both the exhaust and compression stroke) the piston/crank doesn't know or care which TDC is compression or exhaust. In other words, the only difference between the compression TDC and the exhaust TDC is 180 degrees of cam rotation.

[BSTURDIVANT]

Exactly!!

[BSTURDIVANT]

You can compare the cam lobe position at TDC with another cam to see if the sprocket hub has rotated, also you can check to see if the decompressor is trying to open the valve at TDC. Decompressor should be closed at about 2 teeth before TDC(roller past the detent)

[Punk'd]

Originally posted by GPracer2500
It's impossible to be exactly 180 degrees out of time. If you're at TDC on the compression stroke, everything is timed correctly, you remove the cam and reinstall 180 from where you started, all you've done is flip-floped the compression stroke with the exhaust stroke. You'd now be at TDC on the exhaust stroke. Spin the crank 360 degrees and your right back to TDC on the compression stroke with everything still in time even though you removed the cam and spun it 180 degrees.


Ill give that a try, but if I was 180 degrees off, my lobes would be pointing towards the front of my bike correct?

If so that is not the case. My lobes are facing towards the back of the quad.

[pug288]

It's the cam mine did the same thing. Took the hrc out and stock in and it cranked right up!

[Punk'd]

Originally posted by pug288
It's the cam mine did the same thing. Took the hrc out and stock in and it cranked right up!

I have a feeling it is to.. What do you think happened?

[duke416ex]

Originally posted by GPracer2500
It's impossible to be exactly 180 degrees out of time. If you're at TDC on the compression stroke, everything is timed correctly, you remove the cam and reinstall 180 from where you started, all you've done is flip-floped the compression stroke with the exhaust stroke. You'd now be at TDC on the exhaust stroke. Spin the crank 360 degrees and your right back to TDC on the compression stroke with everything still in time even though you removed the cam and spun it 180 degrees.

Since the plug fires every stroke (i.e. both the exhaust and compression stroke) the piston/crank doesn't know or care which TDC is compression or exhaust. In other words, the only difference between the compression TDC and the exhaust TDC is 180 degrees of cam rotation.

Look at your aviator, it contradicts what you say. I promise you if the cam is 180 out, it will not start, how do I know from experience. When the cam is 180 out the valves are opening at the wrong time. This is nothing for me to argue about, I was just trying to help the guy out. I know it works that way cause I have put "flip flopped" them around before and they won't start. The cam only opens the intake one turn of the camshaft, so if the cam is 180 around on teh stroke it will be opening the valves at the wrong times.

[GPracer2500]

Originally posted by duke416ex
Look at your aviator, it contradicts what you say. I promise you if the cam is 180 out, it will not start, how do I know from experience. When the cam is 180 out the valves are opening at the wrong time. This is nothing for me to argue about, I was just trying to help the guy out. I know it works that way cause I have put "flip flopped" them around before and they won't start. The cam only opens the intake one turn of the camshaft, so if the cam is 180 around on teh stroke it will be opening the valves at the wrong times. Like I said, moving the cam 180 degrees just flips the compression stroke with the exhaust stroke. The cam spins at exactly 1/2 speed of the crank. So, for every 360 degrees of crank rotation the cam only spins 180 degrees. In other words, spinning the cam 180 degrees is the same thing as spinning the crank 360 degrees. Since the exhaust TDC and the compression TDC alternate no matter which one your start on, the next TDC will be the other one.

I'm not sure how else I can explain it with words, but HERE (http://www.exriders.com/vbb/showthread.php?s=&threadid=246253&highlight=impossible) is a recent thread on the subject.

[duke416ex]

Not gonna argue, just saying trouble I have had before.

[GPracer2500]

Originally posted by duke416ex
Not gonna argue, just saying trouble I have had before.

No worries. I welcome hearing about poeples' experience.

[Punk'd]

I think I may have found the problem. Im not sure if its suppost to be like this or what, but check out the diffrence on the hubs.

http://img123.imageshack.us/img123/3558/img14066tp9.jpg

Yes.. No?? :confused: :blah:

[BSTURDIVANT]

Exactly what happened oh the one we had!

[rowlrag]

Originally posted by GPracer2500
Like I said, moving the cam 180 degrees just flips the compression stroke with the exhaust stroke. The cam spins at exactly 1/2 speed of the crank. So, for every 360 degrees of crank rotation the cam only spins 180 degrees. In other words, spinning the cam 180 degrees is the same thing as spinning the crank 360 degrees. Since the exhaust TDC and the compression TDC alternate no matter which one your start on, the next TDC will be the other one.

I'm not sure how else I can explain it with words, but HERE (http://www.exriders.com/vbb/showthread.php?s=&threadid=246253&highlight=impossible) is a recent thread on the subject.
If I'm not mistaken, a 2-stroke engine fires every stroke and a 4st is every other. :confused:

[GPracer2500]

Originally posted by rowlrag
If I'm not mistaken, a 2-stroke engine fires every stroke and a 4st is every other. :confused:

Right--if by "fire" you mean combustion. But on nearly all modern four stroke engines the plug does spark on every (up) stroke. It's sometimes called a "lost spark" ignition system. The plug fires on both up strokes--compression and exhaust. When it fires on the exhaust stroke nothing happens because there is nothing there to burn. Since there is a spark on both up strokes it doesn't matter which TDC is the compression stroke and which is the exhaust stroke. Remember that it's the valve postion (which is determined by the cam) that is the only thing distiguishing the compression and exhaust strokes.

Set the piston at TDC on the compression stroke with everything timed correctly. Without turning the crank you can turn that compression TDC into the exhaust TDC by moving the cam 180 degrees. The engine doesn't care--just spin the crank around another 360 degrees and you're right back to where you started.

Really, I'm at a loss about how to explain this any more clearly.

[rowlrag]

I should have said a 2-stroke fires every revolution, and a 4-stroke every other revolution. I understand your wording in the second paragragh. I have heard of lost spark, a term meaning no-spark. There is a multiple spark at lower rpm on some vehicles, but I have never heard of a spark in a 4 stroke every revolution, where could someone find this info?

[GPracer2500]

I think "wasted spark" is actually the correct term. If you search around using that term I think you'll find what you're looking for.

The component that triggers the spark is the ignition pulse generator. The exciter coil is what actually generates the power used by the ignition coil to create the spark at the plug, but the pulse generator is what tells the CDI when it's time to deliver that energy. Since the pulse generator (and the exciter coil, for that matter) are driven off crank rotation (directly--no gear reduction), the ignition cycle takes place every 360 degrees of crank rotation. In other words, the thing that generates the spark is triggered every 360 degrees not every 720 degrees.

The pulse generator would need to be driven off of the cam (with it's 1/2 crank speed rotation) rather than straight off the crank in order to only get 1 spark per 720 degrees of crank rotation. I believe there were some Honda XR dirt bikes from the 70s/80s that did have the pulse generator on the cam. They didn't have a "wasted spark". I'm not aware of any modern single cylinder four stroke with a CDI igntion system that doesn't produce a "wasted spark". It's just simpler/easier to build and package an ignition system that way. The only disadvantage is that the spark plug wears out faster. But they're already so durable that no one really cares.

To clarify, when I said, "...nearly all modern four stroke engines..." in my last post I was talking about ATV engines. A muilti cylinder engine that has a distributer or a really smart "CDI" may not have any "lost sparks". But some will because of 2 plugs (who's pistons are on different strokes) sharing the same coil.

The last paragraph is what applies to our ATV engines:
http://en.wikipedia.org/wiki/Wasted_spark

[Punk'd]

So do you guys think thats the problem? Or is the Hotcam hub suppost to be like that?

(Look at the picture)^^

[rowlrag]

Your cam is junk, like Sturdivant said in the first page.

[rowlrag]

I didn't mean that to sound rude, sorry:(

[lumi]

i would say increasing the decomp stock gap up alittle, get it to stock and than up it a couple feeler size. that should help.



-lumi

[Punk'd]

Got it running!! BUT now it smokes:ermm: There some some white gunk in the sight glass so i guess ill replace the gaskets and piston rings even though that piston and rings is pretty much brand new:huh

Its a Wiseco 11.5:1 Is there such thing as tuffer rings?

[BSTURDIVANT]

check yoyr cylinder- probably cracked when the valves hit the piston! It cocks the piston to the exhaust side and will crack the cylinder!